Aperture-defining form



Nov. 23, 1954 w. F. CHRISTIANSEN APERTURE-DEFINING FORM Filed May 22., 1950 IN VEN TOR.

WILLIAM F CHE/SWANSEA! ATTORNEY United States Patent Ofiice Patented Nov. 23, 1954 APERTURE-DEFINING FORM William F. Christiansen, Vallejo, Calif. Application May 22, 1950, SerialNo; 163,360 1 Claim. (c1. 25-428) This invention relates to an improved aperture-dcfining form for use in pour-ing cementitious structures, such as walls, floors and ceilings.

The invention solves important problems in the building industry. Practically every concrete floor, wall, and ceiling has to have some apertures through which the plumbing pipes and the electrical conduits may pass. If the floor is molded solid, a hole has to be knocked through it; so it has become common practice to use aperture-defining forms. When the concrete is poured around these forms, they define a passageway through the otherwise solid slab, and the concrete is prevented from. entering this passageway.

One trouble with forms heretofore in use has been that it has taken too long to remove them after the floor has solidified. They have tended to bond to the, concrete and have had overhanging parts that became embedded in the concrete, so that it has taken several minutes to take out each form. Since there are often several hundred of such openings in a single building, several man'- days of work have often been consumed just in getting these aperture-defining forms out of the floors and walls. Sometimes the bond between the concrete and the form has been so tight or parts of the form have been so deeply embedded in the cement, that when the form was removed the surrounding concrete was partially destroyed. The present invention solves. this problem by providing a form that does not bond with the concrete and'can be removed in a few seconds without damage-to the cement.

Another problem met in the forms heretofore in use is that they have also taken too long to install andhave usually required special tools; The form of the present invention meets that problem, for it is easily and'quickly installed with a minimum of standard tools.

Still another problem has been thatwhen such forms were installed, they tended to get out of alignment before or during the time when the concrete was poured, so that the apertures often were crooked and sometimes became partly filled with concrete. It has. been especially difficult to keep aperture-defining forms aligned. in. those floor constructions where no top form is used, because there the alignment of theaperture form has to be main.- tained solely by the bottom floor form. The .present invention includes positive means for maintaining the forms in alignment evenwhen thereis no top form.

Another problem has been to provide a form which is inexpensive, so that it can be thrown away after use, and yet is still leak-proof and is strong enough to withstand the pressure of the concrete.

This and the other problems have been solved in the present invention. This aperture-defining form includes a paper or cardboard tube closed at each end by a special type of metal cap. Each cap is inset to provide a shoulder or a plurality of depending nipples that serve to align the tube or body member. The cap also has a covering flange that extends out to about the edge of the wall of the tube or body member. Both caps have a central aperture through which a lag bolt or other securing member may be passed so as to hold the aperture-defining form to the main structural form. Preferably a large washer is used over the upper or outer cap to aid in obtaining a tight seal.

Other objects and advantages of the invention will appear from the following description of a few preferred embodiments. In accordance with United States Revised Statutes, Section 4888, a complete illustrative description is given, but it is not intended to narrowly limit the invention to the illustrations given. The scope of the invention will appear from the appended claim.

In the drawings:

Fig. 1 is an exploded view in perspective of an aperture-defining form embodying the principles of the invention, shown with both of the caps lifted off the body member.

Fig. 2 is a view in elevation and in section showing the aperture-defining form of Fig. l secured in place on a bottom floor form; Fig. 2 also shows a portion of the show the cap more clearly.

Fig. 5 is a view similar to the upper half of Fig. 2 showing another modified example of the invention; and

Fig. 6 is a perspective view from below of the cap shown in Fig. 5.

The aperture-defining form shown in Figs. 1 and 2 includes a body member 10 preferably made from paper or cardboard. I prefer that the body 10 be cylindrical, but this is not always necessary. Its dimensions depend onits use. Typical tubes 10 of this type vary from about four to fourteen inches in height, and from about two to eight inches in outside diameter. The tube 10 has a wall thickness of aboutone quarter of an inch. The outer surface 11 and the inner surface 12 are water proofed, preferably by a coating of wax, asphalt, or tar of a type that does not stick to concrete easily. The waterproofing helps hold the shape of the tube 10 during the molding operation, by preventing the disintegration or softening of the paper or cardboard walls. It also facilitates the removal of theform because properly waterproofed material will not bond to or adhere to the cement around it. The body 10 can therefore be pried loose quickly and slipped out easily when the cement is dry.

As Fig. 1 shows, each end of the bodymember 10 is closed by a cap 15. The cap 15 may be made from thin sheet metal, preferably iron, and may be painted, lacquered, or galvanized to prevent rusting. The cap 15 has an annular outer flange 16 which substantially covers the wall of the tube 10 extending to or slightly short of its outside diameter. In other words, the width of the flange 16 is equal to or slightly narrower than the wall thickness of the tube 10. This greatly facilitates the removal of the lids 15, because they do not extend into the concrete floor and therefore do not become embedded in the concrete surrounding the aperture.

Radially inwardly from the flange, the lid 15 is depressed to provide an annular shoulder 17. The shoulder 17 is located at the inner side of the annular flange 16. It is adapted to fit snugly against the inner wall surface 12 of the tube 10 so as to maintain it in alignment. It may be about one quarter of an inch deep, and it also serves to complete the closure of the open ends of the tube 10.

Preferably the depressed portion of the lid 15 is dished back out into a raised portion 18, which may be approximately on a level with the flange 16. A central aperture 19 is provided, and through it a lag bolt 20 may be passed.

Fig. 2 shows an installation of the form shown in Fig. l. The form is set on top of a bottom floor form 21. (A wall installation is not shown, but it is similar, except that there are forms on each side.) A large washer 22 preferably is placed on top of the upper cap 15. The washer 22 is not needed if the cap 15 is made of stiff enough material, but usually it is preferred to use lightweight disposable caps 15 and to salvage the washers 22 together with the bolts 20. As shown in Fig. 2, the washer 22 rests on the flange 16, and when the bolt 20 1s screwed into the wood 21, the washer secures a tight closure of the lids 15 on the body 10, without any strain on the lids themselves.

The aperture-defining form is usually sold as a unit, comprising the body member and the two caps 15. A desired number of the reusable washers 22, and lag bolts 20 are also purchased for the job, because they may be used repeatedly, but the body 10 and caps are usually thrown away after each use. No special tools are needed for its installation. The head 23 of the bolt may be turned with a wrench or with pliers, or the head may be slotted and a screw driver used.

When the form is in place, the concrete may be poured around it. The cap 15, washer 22, and bolt prevent disalignment of the tubes 10. The shoulders 17 secure the lateral alignment, the flanges 16 and the bolt washer combination tighten down and hold it in place. The caps 15 seal the open ends of the body member 10, especially when they are bolted down and the washer 22 is pressing on the flanges 16 of the upper cap 15. The waterproofed paper walls of the tube 10 are strong and the shape is not affected by wet cement.

When the concrete floor 25 has been poured and has hardened, the aperture form may be quickly removed. To accomplish this, the lag bolt 20 is first removed, and the washer 22 and the upper cap 15 may then be lifted off. When the bottom form 21 is removed, the lower lid 15 may fall off or may be poked out from above by a single sharp blow. Then a screwdriver may be inserted between the tubes outer wall 11 and the concrete 25, so as to collapse or break in the wall of the tube 10 in two or more places. Only a few strokes of a screwdriver are needed, and the entire tube 10 will then fall out. The waxed surface 12 does not stick to the concrete 25, and the paper wall, while strong enough to withstand the fluid pressure of the concrete without deformation, is rapidly torn, bent apart, or collapsed. The whole installation takes about five or ten seconds per form and the removal may be done in between three and twenty seconds, depending on the size of the aperture. This contrasts with the several minutes required for the removal of the best aperture-defining forms heretofore in use.

A modified type of lid is shown in Fig. 3. The lid 30 is exactly like the lid 15 except for the raised radial ribs 31. It has a flange 32 like the flange 16 and a shoulder 33 like the shoulder 17. The ribs 31 extend radially inwardly from near the shoulder 33 over the dished-out portion 34 and nearly to the bolt aperture 35.

The ribs 31 give suflicient strength to the lid 30 so that a large washer like the washer 22 is unnecessary, and a small central washer 36 is all that is needed. For some lids 30 of this type no washer is needed at all. The installation and removal are quite similar to that already described in connection with Fig. 2.

Another modified example of aperture-defining form is shown in Fig. 4. The tube 10 is the same as in Figs. 1 and 2; only the lid 40 is different. The lid 40 has a flange 41 and shoulder 42 like the flange 16 and shoulder 17 of the lid 15, but the center portion 43 of the lid 40 is not dished back. This lid is not so strong as the lids 15 and 30 and does not have the spring action given by the dishing 18 on the lid 15 and the dishing 34 on the lid 30, but it is satisfactory'where the lid 40 is made from sufliciently thick and strong material. Its

outer flange 41 still stops at or short of the edge of the tubes outer surface 11, so that the cap 40 does notextend into the concrete floor and will lift off when the bolt 20 is removed. The shoulder 42 also assures perfect alignment of the tube 10. The large washer 22 is used exactly as in Fig. 2, and the installation and removal are the same also.

Another modified example is shown in Figs. 5 and 6, where another type of lid 50 is employed. The lid 50 is generally flat and extends across the tube 10. The edge 51 of the lid 50 extends to or just short of the outer surface 11 of the tube 10. Instead of having a shoulder 17, a series of nipples 52 are provided by depressing portions of the lid 50, without breaking through the lid. Then nipples 52 are positioned so as to abut the inner wall 12 of the tube 10 and keep the form aligned in the same manner as the shoulder 17 in the cap 15. As this type of lid illustrates, the shoulder or aligning means does not have to be continuous. t usually uses the washer 22, and its installation and removal are as described in connection with Fig. 2.

What is claimed is: l

An aperture-providing form for use in the pouring of cement structures, such as walls, floors and the like; comprising in combination a collapsible cylindrical tube of heavy waterproofed paper of substantial thickness and being open at both ends, a removable thin metal cap for closing each of said open ends, each cap including a radially disposed marginal flange for hearing engagement with the respective end of the tube, each cap further including an axially inset portion bounded by a cylindrical wall snugly engageable within the respective end of the tube for resisting radial collapse of the tube and a substantially rigid thrust washer disposed in overlying relation to one of said caps with its peripheral portion bearing on the radially disposed flange thereof, said caps and washer being provided with centrally disposed axially aligned apertures, and a headed bolt of substantially greater length than said tube adapted to extend through said apertures with one end thereof engageable within a wood form and the head of the bolt bearing against said rigid thrust washer whereby the adjacent relatively thin cap is not subjected to axial tension in the bolt.

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